I secure the bottom of the lace to the bottom hole with a stunsil 
tack bend knot (sorry...I learned these knots in college sailing, and 
that IS the knot I use...designed for holding the main halyard to the 
eye at the top of the sail...as you pull on it, it only gets tighter, 
yet you can remove it easily when desired).  It's sort of like a 
clove hitch, but you end with the loose end of the string between the 
loops of the knot, and the loop made with of the string nearest the 
end of the string to the inside...for strength.